Snap switch with thermal release



May 30, 1933. M GUETT 1,911,893

SNAP SWITCH WITH THERMAL RELEASE Filed Deo. 5, 1930 l NVENTOR #MM MMM Patented May 30, 1933 UNITED STATES PATENT OFFICE MONROE GUETT, OF HARTFORD, CONNECTICUT, ASS-IGNOR T THE ARROW-HART & HEGEM'AN ELECTRIC COMPANY, OF HARTFORD, CONNECTICUT, A CORPORATION OE CONNECTICUT SNAP SWITCH WITH THERMAL RELEASE Application filed December 5, 1930. Serial No. 500,352.

This invention relates to circuit breakers automatically upon the occurrence of a predetermined overload. More particularly this' invention relates to switches of the above type in which the tripping of the breaker is accomplished by means of the warping of a thermal element.

It is an object of my invention to reduce the number of parts required to make a switch of the above type. Another object of the invention is to reduce the amount of tension upon the thermal strip and thereby make for greater accuracy in the tripping of the switch. Other objects and advantages of my invention will appear as it is described in connection with the accompanying drawing.

Fig. l is an elevation view of the contact or front face of the switch showing the switch parts as they appear when the switch has been tripped by an overload.

Fig. 2 is a view like Fig. 1 but showing the switch parts in the normal open circuit position of the switch. The closed circuit position of the parts of the switch is also shown in this figure, in dotted lines.

Fig. 3 is an elevation view of the other or rear face of the switch as itis shown in Fig. l.

Fig. 4 is a rear elevation view of the parts ofthe switch as it is shown in Fig. 2.

Fig. 5 is an elevation view of one end of the switch showing the parts when the switch is in closed circuit position.

Fig. 6 is an end elevation view of the other end of the switch showing the switch parts in closed circuit position.

Fig. 7 is a rear elevation sectional view showing the switch, in full lines, in the closed position and in dotted lines, in tripped position.

Fig. 8 is a plan view of the switch with the parts inthe position theyoccupy after the switch has been tripped by an overload.

Fig. 9 is a perspective view of the auxiliary operator of the switch.

Fig. 10 is a perspective view of the switch frame.

Fig. 11 is a detail view of tle contact carrier of the switch..

Referring to the drawing, a switch frame 20, which carries the moving parts of the switch, is mounted on an insulating base 22. On one end of this base are mounted the wire terminal 24 and one stationary switch contact 26. Another stationary switch contact 28 is mounted on the other end of the base. The contact portions of these two contacts 26 and 28 are located in one plane perpendicular to the base and are bridged by a movable switch contact 30, which is actuated by means as hereinafter described.

Electrically connecting the wire terminal 24 and the stationary contact 26 is a heat responsive element, composed of two bimetallic strips each of which has one end gripped between small metallic plates which are secured together by a screw. The other ends of the bi-metallic strips are soldered to the contact 26 and wire terminal 24 respectively. Upon occurrence of an overload in the circuit the thermal element heats, and warps or bends causing its free end to engage a tongue 3l of a latch member 64 and thereby to trip the switch as hereinafter more fully described.

The switch frame 20 is made from sheet metal U-bent and formed as shown in detail l in Fig. 10. The upstanding portions 32 of the frame have arms 34 extending therefrom. Near the middle of these arms V- notch bearings 36 are provided for aiiat, oscillatable, U-shaped contact carrier 38. This carrier is made of sheet metal stamped into the shape shown in Fig. 1l, thereby providing offset bearing shoulders 39 upon which the carrier oscillates, and longitudinal extensions 40 to prevent sidewise movement of the carrier in the bearings 36. In any suitable manner the bridging contact 30 may be secured upon and insulated from lateral extensions 41 which project from one of the longitudinal extensions 40. The mounting of bridging contacts upon, and insulating them from U-shaped members similar to that shown is common in the prior art.

Hence a detailed description of such con 1 struction is unnecessary here.

Oscillatory movement of the carrier 38 isrestricted by its engagement with the sides of the V-notch bearings, 36, the switch being open (see Fig. 3) when the carrier rests against one side of the notch and closed (see Fig. 7) when it rests against the other. Movement of the carrier is caused by the shifting of a coil tension spring 42, one end of which is secured to the cross bar of the carrier 38, while the other is secured to a pivoted auxiliary operator 44 hereinafter more fully described.

The manually actuable main operator of the switch by which the opening and closing of the switch is normally accomplished is a Ll-bent sheet metal member 52 whose legs lie outside of and parallel to the arms of the frame 20, and are pivotally connected thereto near the base of the frame, by pivot pin 53. The cross piece 55 of the operator 52 is provided with a manual member or handle 56 extending upwardly therefrom to facilitate manipulation of the operator. Identical recesses 54 are cut in .each leg of the. manual operator 52 in order that it may swing between the positions it occupies when the switch is open or closed, without engaging the longitudinal extensions 40 of the contact support 38. To limit the movement of the manual operator in opening and closing the switch, a pair of lugs are turned out from each arm 34 of the frame, one lug being turned out at each end of each arm, the lugs 58 limiting movement in the opening direction and lugs 60 limiting movement in the closing direction. e

Pivotally mounted upon and normally movable with the manual operator is the automatically actuable auxiliary operator 44. This auxiliary operator 44 is stamped from sheet' metal, being shaped and U-bent as shown in detail in Fig. 9. The auxiliary operator has one end of the coil spring 42 connected thereto, as hereinbefore stated, and normally moves as a unit with the main operator upon the manual actuation of the main operator. Therefore the switch is opened and closed whenever the main operator 52 causes the upper end of the coil spring 42 to be moved past dead center position, thereby, snapping the carrier 38 and contact 30 between openV and closed circuit position.

For the same purpose as the recesses 54 are provided in the main operator 52, the legs 46 of the auxiliary operator are curved to follow the contour of those recesses; that is, Jfor the purpose of leaving room for free movement of the'contact carrier 38. The cross bar 49 or the auxiliary operator has projecting sidewi'se from it, a finger 50 by which the end of the coil spring 42 is connected to the auxiliary operator. Two short pivot pins 45 passing through the ends of the legs 46 and through the lower portion of the legs of the main operator serve to mount the auxiliary operator pivotally on the main operator.

In order to compel the auxiliary operator normally to move as a unit with the main operator, a U-shaped latch member 64 mova le in the same plane as the auxiliary operator, is mounted pivotally between the legs of the main operator by a pin 65 passing through the legs of the main operator and the legs 68 of the latch. Noses 74 on each of the legs 68'of the latch engage with lugs 48 projecting from each leg 46 of the auxiliary operator to prevent the auxiliary operator from rotating under the action of the coil spring 42 and to compel the auxiliary operator to move in unison with the main operator. On the ends of the latch legs 68 are nubs 70 which engage with pins 72 in the legs of the main actuator to limit the movement imparted to the latch by leaf spring 71 which presses thereupon in such a way as constantly to urge the latch noses 74 into the path of the auxiliary operator.

To move the latch out of engagement with the auxiliary operator a tongue 31 projects obliquely from the cross bar 66 of the latch 64 and engages the thermal element 25. Thus when the thermal element bends sufiiciently it moves the latch out of engagement with the auxiliary operator to cause tripping of the switch as will now be more fully described.

Referring to Figs. 3 and 7, it will be noted that the pivot 45 of the auxiliary operator is located slightly to the left of the line of action of the spring 42 Whether the switch is closed or open. Thus the auxiliary operator is constantly urged to rotate clockwise. At such times as the auxiliary operator is compelled to move as a unit with the manual operator, as is normally the case, the location of the pivot 45 is immaterial since both operators move about the main operators pivot 53 as the main operator is manually actuated between open and closed circuit position. The parts of the switch are so proportioned and located'that the line of action of the coil spring passes to the left of the manual operators pivot 53 and to the right of the auxiliary operators pivot 45, when the switch is closed. Thus the manual operator is urged toward closed position and the auxiliary operator is urged toward open position, but since the auxiliary operator is mounted on and (for the moment) latched to the main operator, the auxiliary operator must remain in closed circuit position with the main operator.

When the switch is in closed circuit position and an overload occurs the auxiliary operator is freed for movement independent of the main actuator. Then the coil spring 42 acting on the auxiliary operator 44 moves that operators spring engaged end clockwise, (still referring to Figs. 3 and 7) until it is halted by its cross bar 49 striking peaks 62 upstanding from the switch frame arms 34. By ,that time the line of action of the spring 42 has passed from the left to the right of the bearing 36 of the contact carrier 38, causing that carrier to be snapped from the full line position of Fig. 7 to the dotted line position of that figure, thus disengagmg the movable from the fixed contacts. tripping of the switch is accomplished with- 4 out movement to the handle 56.

To reset the switch the handle must be moved tofo position (Fig. 2) and back to on position (Fi 7) when the thermal element 25 has coo ed and straightened. During the resetting'movement the spring 71` pressing the latch 64 causes the nose 74 to engage and fall behind the lugs 48 of the auxiliary operator 44 and thus latch the auxiliary operator to the main operator and compel it to move as a unit therewith. s

From the foregoing it will be seen that during manual operation of the switch, that is, when the main operator and auxiliary operator move together, the upper end of the coil spring 42 will be moved between a position to the right of the notch bearing of the contact carrier 38 (open circuit, full lineposition of Fig. 4),.to a position at the left of that bearing (closed circuit, dotted line position Fig. 4), as the handle 56 is moved between open and closed circuit positions. Each time the upper end of the spring passes the dead center, that is, passes through the plane of the contact carrier 38, the switch will be actuated with a snap action to open or close the switch.

In order that the switch may be adjusted to trip on higher or lower current values, the end of the tongue 31 of the latch 64 is tapped to receive a screw 33, the head of which engages with theinsulating knob 35 on the end of the thermal element 25. By screwing the screw in or out farther, the degree of rotation necessary7 to disengage the latch nose 74 from the lug 48 on the auxiliary member may be varied and hence the point or current value at which tripping will occur will be varied accordingly.

From the foregoing the principle and construction of my invention will be readily understood. Be it understood however, that many modifications within the scope of my invention will occur to those skilled in the art. Therefore I do not limit myself to the specific construction shown.

I claim z- 1. In a manually and automatically operable switch, a switch frame, a manually operable member pivotally mounted on said frame, an automatically operable member pivoted on said manually operable member, a contact carrier pivotally mounted on said frame, and a spring connecting said auto- This l matically operable member and ,said'contact carrier.

2. A manually and automatically operable switch, comprising fixed and movable conthe switch is closed to move said automaticaL.U

ly operable means in direction to disengage said fixed andmovable contacts, and means holding said automatically operable means against movement except upon occurrence of an overload or upon manualv movement of the switchto open circuit position.

3. A manually and automatically actuable switch having fixed and movable contacts, means manually to actuate said movable contact, means to actuate automatically said movable Contact, said automatic means normally moving asa unit with said manual means, means normally urging said automatic means toward open circuit position, said urging means being permitted to operate upon occurrence of an overload, movement of said. automatic means toward open circuit position being succeeded by movement of said movable contact to open circuit position.

4. A manually and automatically operable.

switch comprising a frame, a manually actuable operator, mounted on said frame, a bridging contact, and two stationary contacts adapted to be bridged thereby, a carrier for said bridging contact pivotally mounted in said frame, an auxiliary operator normally latched to said manual operator, but adapted to be free for independent movement upon occurrence of an overload, and spring means causing movement of said bridging contact with a snap action.

5. A manually and automatically operable switch comprising fixed and movable contacts, said movable contact being pivoted about an axis fixed relative to said fixed contacts,manually actuable means to operate said movable Contact under normal conditions, means automatically to operate said movable contact upon occurrence of an overload in the circuit, spring means tending when the switch` is closed to move said automatically operable means in direction to disengage said fixed and movable contacts, and means latching said automatically operable means to said manually operable means until neem-rence of an overload.

6. A manually and automatically actuable switch having fixed and movable contacts, said movable contact being pivoted about an axis fixed relative to said fixed contacts,

means to actuate manually said movable contact, means to actuate automatically said movble" contact, said automatic means bein carried by said manual means but capa le of movement independent thereof upon occur- 5 rence of overload.

means to actuate manually said movable contact, means to actuate automatically said movable contact, said automatic means bein carried by said manual means but capab e of movement independent thereof upon occurrence of overload, and a spring connecting said automatic means and said movable contact to cause snap movement of said movable contact.

8. A manually and automatically operable switch having fixed and movable contacts, a U-shaped switch frame, a U-shaped manual operator pivoted on said frame, a U-shaped auxiliary operator pivoted to said manual actuator, a U-shaped carrier for said movable contact pivoted in said frame, and spring means to cause engagement and disengagement of said contacts with a snap motion.

9. A manuall and automatically operable switch having fixed and movable contacts, a switch frame, a manual operator pivoted on said frame, an auxiliary operator pivoted on said manual operator, a spring normally urgin said auxiliary o rator to open circuit position, a latch mem r pivoted on said manual operator and engagmg said auxiliary operator, means to trip said latch and allow said switch to open.

10. A manually and automatically operable switch having fixed and movable contacts, a switch frame, a manual operator pivoted on said frame, an auxiliary operator pivoted on said manual operator, a spring normally urging said auxiliary-operator to open circuit position, la latch member pivoted on said manual operator and engaging said auxiliary operator, an overload responsive element adapted to rotate said latch about its pivot and free said auxiliary operator for movement to open circuit position, upon occurrence of an overload.

11. A manually and automatically operable switch having fixed and movable contacts, a switch frame, a carrier for said movable contact pivotally mounted in said frame,

a. manual operator pivoted on said frame, an

auxiliary operator pivoted on said manual operator, a spring normally urging said auxihary operator to open circuit position, a latch member pivoted on said manual operator and engaging said auxiliary o rator` oted about a fixed axis and operable to move the movable contact, a carrier for said movable contact pivotally mounted about a fixed axis, a latched member ivotally mounted about a movable axis and eed for movement about said axis upon occurrence of an overload, a spring connecting the free end of said latched member and said carrier and acting to move said movable contact with a snap upon occurrence of an overload or movement o said manually operable member.

13. A manually and automatically operable switch comprising fixed and movable contacts, a carrier member for said movable contact pivotally mounted about a fixed axis, a manually operable member ivotally mounted about a fixed axis, a pivote latched member, a spring for moving said movable contact with a snap motion, said spring at all tlmes urging said latched member in one direction, means to release said latched member upon occurrence of an overload.

14. A manually and automatically operable switch comprising fixed and movable contacts, a pivoted carrier for said movable contact, a spring, a manually operable member for moving one end of said spring through a dead center position to initiate movement of said carrier with a snap, and a latched member releasable upon overload to move sald spring through dead center position thereby initiating movement of said carrier with a snap.

15. A manually and automatically operable switch comprising fixed and movable contacts, a carrier for said movable contact pivotally mounted about a fixed axis, spring means for moving said carrier with a snap, means normally latched but releasable upon overload to permit said spring means to move said carrier, said s ring means at all times urglng said latch means inone direction, and manually operable means to move said carrier through the agency of said spring means under normal conditions.

16. A manually and automatically operable switch comprising fixed and movable contacts, a reciprocating carrier for said movable contact, spring means for moving said carrier with a snap, a manually movable member for moving said carrier through the agency of said spring means, a latched member releasable upon overload to carry said spring means through a dead center position to initiate movement of said carrier with a snap.

17. A manually and Vautomatically operable switch comprising fixed and movable contacts, a reciprocating carrier for said movable contact, a spring for moving said carrier, with a snap, a manually movable member for moving said spring through dead center position to move said carrier, a latched member secured to said manual member and releasable upon overload to permit said spring means to move said carrier with a snap.

18. A manually and automatically operable switch comprising fixed and movable contacts, a reciprocating carrier 'for said movable contact, a spring for moving said carrier with 4a snap, a manually movable member for moving said spring through dead center position to move said carrier, a latched member secured to said manual member, a latch for said latched member pivotallyl mounted on and carried by said manual member and releasable upon overload, to cause movement of said carriers under the influence of said spring. f

19.- An electric switch comprising lixed and movable contacts, movable-contact-carrying means, spring means, manually movable means, spring-stressed means normally movable with said manually movable means to carry said spring means through dead center position to actuate said movable contact with a snap, said spring pressed means being released upon overload to carry said spring means through dead center position independent of said manually movable means.

In testimony whereof I have signed ,my name to this specification.

' MONROE GUETT.

DISCLAIMER 1,911,893.M0nroe Guett, Hartford, Conn. SNAP Swrrca WITH TERMINAL RELEASE. Patent dated May 30, 1933. Disclaimer filed September 27, 1935, by the assignee, The Arrow-Hart de Hegemam, Electric Company.

- Hereby enters this disclaimer to claim 8 of the aforesaid Letters Patent which is 1n the following words: y

8. manually and. automatically operable switch having fixed and movable contacts, a U-shaped s wltch frame, a U-shaped manual operator pivoted on said frame, a U-shaped auxlliary operator pivoted to said manual actuator, a U-shaped carrier for said movable contact pivoted in said frame, and spring meansto cause engagement and dlsenga ement of said contacts with a snap motion.

[O cwl Gazette Octoer 22, 1.935.] e 

